The first man to set foot on the Moon is ‘doing great’ after the operation, according to Nasa.

After turning 82 last weekend, Mr Armstrong was scheduled in for a heart bypass operation on Tuesday and is now faring well, NBC news reports his wife Carol as saying.

The former astronaut made history when he landed on the Moon on July 20 1969 as part of the Apollo 11 mission.

As commander he was given the task of setting foot outside and was filmed climbing down the stairs onto the dusty surface, uttering the famous phrase: ‘That’s one small step for a man, one giant leap for mankind.’

Following his operation, Nasa administrator Charles Boden called Mr Armstrong a ‘true American hero’ and wished him a quick recovery.

In a statement he said: ‘Neil’s pioneering spirit will surely serve him well in this challenging time and the entire Nasa family is holding the Armstrong family in our thoughts and prayers.’

Mr Armstrong now lives with his wife in the Cincinnati area and after leaving the space agency went on to enjoy a long and prestigious career teaching at the university there.